Flash an ESP32 from your browser

Synacl flashes firmware directly from the browser using the Web Serial API — no drivers or build tools.

1. Use a Chromium-based browser (Chrome/Edge). Web Serial isn't available in Firefox or Safari.
2. Connect the ESP32 to your computer over USB.
3. On Gateways → Add gateway, click Flash, then pick the serial port when prompted.
4. The flasher writes the firmware and reads back the board's chip ID, which becomes the gateway's identity.

Next: provision Wi-Fi. If the port doesn't appear, see Web Serial isn't working.

Re-flashing an existing gateway

You can re-flash a gateway that's already registered — useful when it can't take an over-the-air update because it's offline or stuck.

• On the Gateways page, use the Flash via USB action on the gateway's card, or open Add gateway and pick it under "Re-flashing an existing gateway?".
• A banner shows exactly which firmware version will be flashed before you click Flash.
• The build follows the gateway's firmware channel: a gateway on the Beta channel (with beta access enabled for your account) gets the latest beta build; otherwise the latest stable. New gateways always get stable.
• Re-flashing preserves the gateway's Wi-Fi and MQTT settings, so you don't need to re-register or re-provision it — steps 2–3 of the Add gateway page are only needed if you want to change those.